A parking lock is known from DE 10 2010 053 857 A1. A similar solution is disclosed by DE 10 2011 080 498 A1. In the latter solution, a rolling planet transmission is used as a mechanical transmission element for transmitting the movement of the actuator to the locking pawl. This makes it possible to implement relatively high transmission forces.
When parking a vehicle, e.g. on a slope, the vehicle weight produces a force on the closed pawl and thus, in turn, on the parking lock mechanism, depending on the wheel diameter, the transmission ratio and the radius of the locking wheel (locking tooth system). When unlocking the parking lock on the slope, this applied force must thus be overcome. Since the aim is to make the actuator as small as possible in respect of power and of current consumption, so that the actuator can still be operated with the voltage and current consumption of the onboard battery in an emergency, only a restricted unlocking force is available. This, in turn, can only be increased to a limited extent by means of the transmission ratio since otherwise the required actuating travels of the mechanism are not sufficient.
To disengage the locking pawl, i.e. to move the latter into the unlocked position, a parking may thus require a relatively large force. This can be obtained from the relative geometry of the pawl tooth and the recess in the locking tooth system, namely by means of a corresponding undercut angle. A high force can also be obtained by virtue of the friction conditions and the friction wedge achieved.
In the solution according to the cited DE 10 2011 080 498 A1, it is admittedly possible to achieve high transmission forces in order to move the locking pawl, especially from the locked position into the unlocked position. However, the construction of this solution is relatively complex and thus expensive. Furthermore, the arrangement disadvantageously has a relatively high weight.
To overcome this disadvantage, US 2008/0169168 A1 discloses the practice of implementing the actuation of the parking lock with a crank mechanism. When the automatic selector lever is placed in the parking position, the movement determined by the driver is implemented. The preset construction requires a large number of components and a considerable installation space, especially axial installation space.